The present invention relates generally to surface or ground-engaging implements and specifically to agricultural row-crop planting implements. Although this disclosure is directed primarily towards application in the setting of a row-crop planting implement, the present invention may find application in any setting wherein dynamic control of excess downpressure upon guide structures is desired. Examples include manufacturing processes wherein controlled material cutting or scoring is required across a surface that presents a variable surface profile or a surface having a spatially variable load-bearing strength or hardness.
Producers of agricultural row crops select planting space between seeds within a row in accordance with a predetermined row width and a desired plant population per acre of land. Due to high populations of plants within a given row, competition between plants for available sunlight, soil moisture, and soil nutrients often plays an important role in the growth and development of individual plants. Competition between plants, each provided equal opportunity, can produce positive results. For example, forestry engineers make use of controlled population pressure to force the tall straight growth of trees. Competition can, however, produce negative effects. For example, it is generally believed that overall production per acre of corn is compromised if equal opportunity is not provided for each competing plant. If the emergence of a seed in the row is delayed 24 hours relative to other seeds nearby, total yield for the plants in that segment of row may be measurably reduced. Also, if the emergence of a single seed is delayed 48 hours, relative to the seeds nearby, remaining yield potential may be best protected by destroying the delayed plant. Agricultural producers thus have a clear and definite interest in practices that produce or favor not only an optimum growing environment for all seeds generally, but an equal opportunity for each seed and resulting plant.
The system disclosed herein provides for the dynamic control of excess downpressure applied to a surface-engaging depth control structure that is used in combination with a surface-penetrating instrument. In the agricultural setting, this system addresses an important aspect of the producers"" interest in providing an equal environment and opportunity for each plant, namely, providing uniform depth of seed placement. This new system expands the producers"" opportunities to manage the effects of the several variable factors that commonly affect the depth of seed placement. A discussion of a typical planting unit that may benefit from the present invention, namely, a row crop planting unit, is provided below.
FIG. 1 (prior art) illustrates a typical row crop planting unit, the basic components, relative placement, and function of which are in widespread use and commonly known. In reference to FIG. 1, a toolbar 2, is shown. The toolbar 2 is a structural element to which additional functional elements are connected. The toolbar""s position is generally parallel to, and typically approximately 20 inches above, the surface of the soil 14. Of course, depending on the application, this height may vary dramatically. Typical toolbars 2 are supported by wheels and a lift system (not shown). The toolbar 2 is typically pulled forward by a tractor 50 (in the direction of the viewer""s left) by means of a hitch (not shown). The primary function of the toolbar 2 is to support row unit(s) 4. Typically, a plurality of row units 4 are attached to the rear (the viewer""s right) of the toolbar 2. In practice, a given toolbar 2 is used to support and pull numerous row units 4 that are positioned generally parallel to one another.
The main frame 6 of the row unit 4 is attached to the rear of the toolbar 2 by means of two pairs of parallel linkages 8, each pair being pivotal at both ends. In FIG. 1 (prior art), only the left pair of parallel linkages 8 is shown. Attached between the top and bottom portions of the parallel linkages 8 are adjustable, supplemental downpressure springs 10. The adjustable, supplemental downpressure springs 10 are typically attached at a fixed point 24 on one of the parallel linkages 8, and at one of several selectable attachment points 22 on the paired parallel linkage 8.
As the row unit 4 is drawn forward a linear, xe2x80x9cVxe2x80x9d-shaped opening or furrow (into which seeds may be dropped) is created in the surface of the soil 14 by what is well known in the row crop planter industry as a double disk opener 12. Other furrow forming means, for example, single disk openers or wedge-shaped implements, may also be employed to form furrows. Double disk openers 12 typically comprise a pair of rotating disks mounted in angled relationship to one another to form a driving wedge that may be moved through the soil. The left hand disk of the double disk opener 12 is shown in the side elevation view of FIG. 1. The double disk opener 12 may produce the linear xe2x80x9cVxe2x80x9d shaped opening or furrow in the soil surface due to the particular orientation of one rotating disk relative to the other. This relationship is generally fixed by the disks"" mounting to the row unit main frame 6. The horizontal distance between the centers of the two separate disks of the double disk opener 6 is generally one to several inches. The generally intersecting axes about which each disk of the double disk opener respectively and independently rotates are typically vertically fixed in relation to the row unit main frame 6. The angled relationship between the disks (that form the wedge) typically brings the edges of the two disks into contact or closest relationship with each other at the opener disk cutting edge 16 where the disks enter and penetrate the soil surface 14. The effectiveness of the double disk opener 12 as herein generally described, is well established by its numerous applications and extensive use over several decades. In addition, such planting units often include a third, contoured, ground-breaking disk (not shown) that may be mounted to cut through and loosen the soil in front of the dual-disk wedge.
Equally well established is the use and function of adjustable gauge wheels 18 (a left one of which is shown in FIG. 1 (prior art)) mounted generally parallel to or in slightly angled relationship with, and in some applications, in side contact with, the disks of the double disk opener 12. Whereas the mounting location of the double disk opener 12 to the row unit main frame 6 is generally fixed by its manufacturer or user, the mounting location of the depth gauge wheels 18 relative to the row unit main frame 6 is generally vertically adjustable. This adjustment allows for the positioning of the lowermost point of a depth gauge wheel 18 at a distance between about zero and three inches (or other desired planting depth) above the lowermost point on an opener disk cutting edge 16. It is possible, then, by means of vertical adjustment of the gauge wheels 18 to control the depth of penetration of the double disk opener 12 into, and a selected distance beyond, the surface of the soil 14. In this manner, the gauge wheels 18 are relied on to support a portion of the weight of the row unit 4 upon the soil surface 14. A portion of the weight of the row unit generally is supported by other means such as the toolbar.
Although reference is made above to double disk openers 12 wherein disks are fixed in vertical relationship with the main frame, various suspension systems are disclosed in the prior art that relate to gauge wheel 18 and disk 12 suspensions. For example, U.S. Pat. No. 5,235,922 discloses a planter with an equalizer between gauge wheels. In the ""922 patent, gauge wheels are controlled by an equalizer arm that is connected to a main frame. In FIG. 4 of the ""922 patent, disks are shown in suspension with gauge wheel supports and equalizer structures. The present invention may find application with equalized or compensating suspensions such as the suspension of the ""922 patent, with independent gauge wheel suspensions, or with non-equalized, non-independent suspensions.
The total vertical force necessary to cause the double disk opener 12 to penetrate the soil surface 14 to a desired uniform depth is generally referred to as xe2x80x9cdownpressurexe2x80x9d. Extreme variation in soil types, soil moisture levels, and soil compaction or looseness (due, for example, to prior tillage operations) are only a few of the various factors that provide varying resistance to the penetration of the soil surface 14 by the double disk opener 12. To date, it has generally been the planting machine operator""s task to determine the desirable, necessary, and effective level of downpressure, and to manually adjust downpressure accordingly.
Primary sources of downpressure include the weight of unused seed, the weight of the row unit, and pressure from supplemental downpressure sources (springs, hydraulic cylinders, air bags, etc.). The row unit 4, attached to the toolbar 2 by means of the pairs of pivotal parallel links 8, is designed to respond vertically to the numerous large and small variations in the levelness and smoothness of the soil surface 14. Accordingly, if row units 4 were attached rigidly to the toolbar 2 and if row units 4 were forced to function without the benefit of responsive depth gauge wheels 18, variations in the levelness and smoothness of the soil surface 14 would result in dramatic soil penetration depth variations or dramatic shifts in gauge wheel loadings. Therefore, it may be seen that the first source of downpressure available to the rotating double disk openers 12 is the independently exerted, fixed weight of the row unit 4, plus any permanent attachments.
Next, the seed reservoir 20 (typically mounted at the top of the row unit 4) provides a supply of seed to be planted. The weight of this seed provides the second source of downpressure to be applied to the double disk opener 12. It is significant to note, however, that the amount of downpressure available from the seed in the seed reservoir 20 varies in proportion to the quantity of unused seed remaining in the seed reservoir 20 at a given point in time. This inherent variation in the quantity of available downpressure from this second source historically has added complexity to the seed planting machine operator""s task in selecting the desirable level of downpressure necessary to produce the desired uniform seed depth.
The third source of downpressure, supplemental downpressure, may be provided by various exemplary force-assist means including springs 10, hydraulic cylinders 26, and air bags 28. These sources are referred to as supplemental downpressure sources.
The depth gauge wheels 18 preferably carry some quantity of downpressure in excess of that needed to cause the double disk opener 12 to penetrate the soil surface 14 to the full distance selected by the vertical setting of the depth gauge wheel 18. If the depth gauge wheels 18 (functioning as a depth-regulation member) carry no such excess downpressure or weight, the full preset depth of penetration of the double disk opener 12 may be compromised. In addition, some quantity of excess downpressure is often useful in crushing soil clods or compressing prior crop organic residue on the soil surface 14. If the depth gauge wheels 18 carry insufficient xe2x80x9cexcessxe2x80x9d downpressure to crush or compress clods and organic residue in their path, the depth gauge wheels 18 would be forced to roll up and over the clod or organic residue, thereby compromising control of the uniform depth of penetration.
If the quantity of total downpressure provided by all sources at a given point in time exceeds the downpressure needed to produce the selected, preset, full depth of penetration and the crushing/compressing of clods and/or organic residue, there are two noteworthy undesirable results. First, unusable excess downpressure may cause needless and avoidable overloading of the depth gauge wheels 18 thereby shortening the useful life of the depth gauge wheels 18, and wasting the useful life of the bearings of the depth gauge wheels 18. Also, too much excess downpressure may cause the unnecessary and undesirable compaction of soil beneath the depth gauge wheels 18 or an undesirably deep seed depth, especially in loose, easily compacted soils. The negative effects of excessive soil compaction, including but not limited to decreased water and nutrient infiltration, decreased root growth, and decreased microbial activity, are well researched and documented.
There is therefore a need for an improved surface engaging device in general, and an improved ground engaging implement in particular that provides dynamic control of excess downpressure to allow operators to enjoy the beneficial aspects of having a sufficient amount of excess downpressure while minimizing the occurrences of the detrimental effects caused by having greater or less excess downpressure than is desired.
A dynamic, user-controllable, variable and responsive downpressure control system is provided to allow an operator to select a level of excess downpressure that, in the operator""s judgment or in accordance with predetermined ground characteristics, maximizes the objectives of uniform depth of seed placement while minimizing the adverse effects associated with too great or too little downpressure. The system utilizes pressure or load sensors placed on the row unit, preferably on an axle or mounting structure associated with gauge wheels, to convey signals that indicate a detected load to a microprocessor that, in turn, may convey signals to a control device (electrical actuator, solenoid valve, etc.) to responsively and dynamically adjust the supplemental downpressure that is applied to the row unit 4 (and, therefore, to the gauge wheels 18). In this manner, an operator may select a desired excess downpressure and the system may dynamically maintain the selected excess downpressure as the planter is in motion and as non-dynamically controlled load sources (seed reservoirs having contents of variable weight and volume, etc.) vary. Further, if used in combination with a Global Positioning System (GPS) and/or field mapping system, site specific excess downpressure values may be selected as appropriate for different sites within a field and the present invention may maintain the desired excess downpressure for the sites or locations through adjustment of the supplemental downpressure responsively to detected loads and predetermined excess downpressure requirements. Finally, because such a system may be used with an operator display and input module, the operator may monitor system performance on an ongoing basis. This monitoring may include readings of electronic feedback regarding the target and applied loads that verify the ongoing and dynamic detection of variable loads as the unit is pulled over uneven surfaces.